updated Python extension versions

var/spack/packages/py-cython/package.py

var/spack/packages/py-dateutil/package.py

var/spack/packages/py-ipython/package.py

var/spack/packages/py-matplotlib/package.py

var/spack/packages/py-nose/package.py

var/spack/packages/py-numpy/package.py

var/spack/packages/py-pandas/package.py

var/spack/packages/py-pygments/package.py

var/spack/packages/py-pylint/package.py

var/spack/packages/py-pytz/package.py

var/spack/packages/py-rpy2/package.py

var/spack/packages/py-scikit-learn/package.py

var/spack/packages/py-scipy/package.py

var/spack/packages/py-setuptools/package.py

var/spack/packages/py-sip/package.py

var/spack/packages/py-virtualenv/package.py

var/spack/packages/python/package.py